In a package, how to call a R function from this package with Rcpp?

Question

The Rcpp quick reference guide shows how to call a R function from a package in a Rcpp code. It takes as example the stats package. But if I do a package and I want to call a R function from this package with Rcpp, also in this package, how should I do? I didn't try, but I guess that following the stats example, simply replacing stats with mypackage, will not work because mypackage does not exist yet during the compilation. I hope my English phrasing is clear...

Answer 1

I set up a quick package tstpkg via a call to kitten.r using the pkgKitten package.

I added this R function:

theAnswer <- function() { 42L }

and indeed we can call it from the same package simply by not prefixing any namespace etc as in

#include <Rcpp/Light>

// [[Rcpp::export]]
bool checkAnswer() {
    Rcpp::Function f("theAnswer");
    int val = Rcpp::as<int>(f());
    return val == 42;
}

A quick ad-hoc call on the command-line confirms:

$ Rscript -e 'library(tstpkg); theAnswer(); checkAnswer()'
[1] 42
[1] TRUE
$